security of ICMP type 9

[johnleee]

don't know how to set on cisco switch and router to prevent ICMP type 9 response / broadcast (router advertisement) from other computers except authorised the domain server? it's a headache when facing a big network while less control. appreciate if anyone has an idea.

[thisisshanky · Accepted solution]

On the router interface, apply an access list which looks somewhat like this...

access-list 101 deny icmp any any 9

access-list 101 permit ip any any

int e0

ip access-group 101 in

For simplicity i have used "any" as the keyword in place of source and destination ip addresses....This could be replaced with an ip address or network address... as appropriate..

Hope that helps.